1. Field of the Invention
The present invention relates to an apparatus, method and computer readable recording medium for performing a digital processing of image information, and more particularly to an apparatus, method and computer readable recording medium for performing a digital processing of image information with a memory control system.
2. Discussion of the Background
With a advancement of a digitalization of an image processing apparatus, such as a copying machine and so forth, processing and editing of image data using an image memory to store image data has become popular. Exemplary devices for processing and editing image data include an electronic sorter device and an image division device. An electronic sorter device memorizes image data of a plurality of original documents in an image memory, and outputs a designated number of copies. The electronic sorter device eliminates the sorting of the copies and produces a plurality of batches of copies of the original documents.
In order to achieve an electronic sort function, a copying apparatus is required to memorize all image data of a plurality of original documents in an image memory. A copying apparatus includes a semiconductor memory as a primary memory device (i.e., a main memory device) which is attached to a CPU (Central Processing Unit). However, because a semiconductor memory is comparatively expensive, a copying apparatus generally includes a secondary memory device (i.e., a supplementary memory device), which supplements a memory capacity of the primary memory device. The copying apparatus uses both primary and secondary memory devices as an image memory. A secondary memory device includes a disk recording medium, such as a hard disk and a MO (magneto-optical disk), which are comparatively cheaper than a semiconductor memory.
A semiconductor memory is used as a buffer memory to absorb a difference between a transfer speed of image data of a secondary memory device and an input/output speed of image data of a copying apparatus. A semiconductor memory is also used to output an image formed according to image data by rotating the image with an address operation during reading out of image data stored in a secondary memory device (i.e., an image rotation function). When an image data transfer speed of a secondary memory device is substantially high compared with an image data input/output speed of a copying apparatus, an input/output image data can be directly stored in a secondary memory device. In this way, such above-noted semiconductor memory is not required. Similarly, when a copying apparatus does not have an image rotation function, such above-noted semiconductor memory is also not required.
In a secondary memory device, data is sequentially stored. When the stored data is randomly read out so as to rotate an image, access speed is substantially lowered such that a speed of an image output, which a copying apparatus may require, may not be satisfied. For example, the invention described in Japanese Patent Laid-Open Publication No. 6-168183 includes a semiconductor memory with a correspondingly smaller memory capacity by controlling an image memory according to processing and editing functions. An apparatus according to the above-mentioned invention includes a table to control a property of each semiconductor memory, which is a frame buffer memory, and a function to temporarily store data, which is stored in a semiconductor memory, in a secondary memory device.
According to the above-noted invention, when a frame buffer memory size larger than a remainder of a frame buffer memory size is required, data stored in a semiconductor memory is temporarily stored in a secondary memory device referring to a property of a semiconductor memory in a table so as to secure a frame buffer memory size necessary for a new job. A status of a job is described in the table, and whether or not data stored in a semiconductor can be temporarily stored in a secondary memory device is judged by the status.
An image division device outputs a plurality of images by dividing image data of an original document, which has been read out by being scanned once by a scanner, into a plurality of images. The processing of an image division is performed by repeating operations in which an image data read out from an original document is temporarily stored in a semiconductor memory, the stored data is read out with an address designated and is output to a printer at the same time.
Based on the above discussion, a digital copying machine having an electronic sort function is often configured to include both a semiconductor memory and a secondary memory device and the capacity of such a semiconductor memory typically equals the amount of data corresponding to the largest possible transfer sheet output by the copying machine. However, even if a semiconductor memory has a memory capacity that can store data of the largest possible output transfer sheet, it is very rare to execute an image rotation for a size of the largest possible output transfer sheet. Further, when a secondary memory device has an access speed that is very much close to an image transfer speed corresponding to a copy speed of a copying machine, it absorbs a speed difference, thereby eliminating a need of a semiconductor memory.
According to the above-noted devices, whether or not data can be temporarily stored in a secondary memory device is judged by comparing a size of a memory. Practically, it is sufficient to have a memory size in which transferred data is temporarily stored until it is output. However, because such devices compare an absolute volume of a memory size, a memory used tends to be larger in a storage capacity so as to secure a larger memory size.
In an image dividing device, image data read out by a single scan is required to be temporarily stored. However, current image dividing functions typically can not be applied to image data stored in a memory device other than a main memory device attached to a CPU. Therefore, a copying apparatus needs to include a semiconductor memory that is large enough to store image data of the largest original document, which a scanner can scan in a single scan. This makes it difficult to downsize a semiconductor memory to be used.